Re: different ads in the same campaign have different avg positions

There are two items that affect avg position and that is quality score and bid. By raising either quality score or bids (to a certain point) will give you a better position. It also depend on the competition for each of the keywords. So if by chance one ad is shown more often for high competition keywords it will more likely have a different avg position.

One of the factors in quality score is Ad Copy. So if one Ad uses keyword in its copy that would increase quality score and give that Ad a better position. You can learn more about Quality score here:

Ad Position, or Rank, is based upon your Keyword Quality Score and your bid so it's those two factors that cause the variation. In very simple terms you can think of Quality Score as being an "adjustment factor" to your bid so, for example, if your bid is $1 and your Quality Score 7/10, your effective bid is $0.70. This bid in turn has an effect upon your Ad position since it competes with other advertisers.

Quality Score is made up of a lot of different factors but some of these relate to the relationship between the Keyword, the search term and the Ad copy (for the Search network) so it's quite possible - likely even - that different Ad/Keyword combinations will have different Quality Scores. It's therefore possible that each Ad could, over time, develop a quite different average position to another.

Re: different ads in the same campaign have different avg positions

I'm assuming here you have very different average position. Not 3.4, 3.8 and 4.2 which is close and within one position of each other but rather 3.4, 4.4 and 5.2 type of stats.

Increasing QS is the other way to increase position. It is a better option than increasing bids. As QS is strongly tied to CTR, you need to create better ads that get clicked more often.

QS is shown at the keyword level but it's the ad that determines if it's clicked on. So the QS is more accurately that of the ad. To be more precise, the QS of each keyword-ad as Jon said. If you have an ad that greatly outperforms another, you can have very different positions as you are experiencing because its QS is placing it higher for the same bid.

I would not have 3 ads active in a group at the same time. That muddles determining which is your better ad too much. Your better placing ad for example could in fact be because it just happens to show more often when one or more of your competitors are not advertising at that moment for whatever reason. So only have two active ads to get a more accurate picture.